[morzh]

We don't know if your base does not function properly. As I said, in my case it is too not super strong and only becomes somewhat strong at good overall volume level, but in your case as you said the volume is weak as a whole.

Cap #136 is the DC blocking cap for the audio out from the 2nd audio to the power amp, it goes from the 2nd audio plate to the output cable and then to the 6F6 driver tube grid. That is, it is the audio signal path from the tuner chassis to the output amp.

I have to see if the 6J5 bass AVC tube in the amp chassis affects the bass level; the second pot attached to the volume pot regulates it.